Separating hafnium from zirconium



United States Patent :SEPARATINGIHAFNIUM FROMI- ZIRI'ZBNIUM BryamXlfreilfJak'llister afldTJames. Francis Duncan,

Stl'anii, Lo'n'ilom'fEngland rNotDrawing.:Applicationalilebruanyfiilolfll, u Serial; No; 212", 029

14 Claims. (C13 13-:1'9)

This invention relates to the ssepariation of zirconium land lhaflllllm:by remployment of lion sexelrange rmethods. See also copendingaapplication'sserialsNo. :ZMMBOJ-filed Febr-uary .21, 1195-1.

Some degree :of separation :of rzirconiurn land hafninm by :such methodsi has lbeen repol te'd by @Street antl Sea- .-.borg:J..:A. C. :8.7.094268 -(11-948 iusingm metho'cl based on elution x by 6'Nhydrochloric i'acid from column 'of aoation exchange tmaterial zknown as.Dowex 50" :and consisting "of 4a ssulphonated 'olystyrene resin; and hy:Kraus and .iMoore-(J. AACJS. '71, 319.68 -E9499) ttsing HimlXUJIBKOfLhydrofluoric sand-hydrochloric acids o elute ta mixture =o"f the .twotelements from a .column o'f anion exchange imaterial.

Eor certain. purposeszzirconinm with very lowihafnium contentrisza:requirement, and methods hitherto 1 available have not simply achievedthe necessary degree of purity.

The -objectt 6f the invention *is to provide '"a method .of.separatinghafniumtfromrziraoniutn wherebymtherlatter may be prepared in a purestate substantially fr'eelfrom .hafnium.

.According vto =the rinvention substantially tcomplete separation ofzirconium from hafnium lmay -.-be obtained :bytelution of:iomexchangednaterial, on' whichecompounds :zOf ithe elements :areadsorbed, \with an (approximately normal solution of sulphuric acid.Preferably :the acid concentration is between 0.8 N and 1.2 N and shouldnot exceed substantially 1.5 N. Increase of the concentration ofsulphate ion in the eluting solution by presence of a soluble sulphate,such as sodium sulphate, has been found to be advantageous.

The preferred ion exchange materials for use according to the inventionare sulphonated polystyrene resins which may be prepared, for example,by the method described in United States Patent No. 2,366,007. Resinswhich may be employed are Dowex 50 and Zeokarb 225. The ion exchangematerial is preferably arranged in the form of a column in a tubethrough which solutions for treatment and eluting solutions are passed.

The following are examples of preferred Ways of carrying the inventioninto effect.

Example 1 A column of ion exchange resin known as Dowex 50 or Zeokarb225 4 feet long is arranged in an inert tube of one inch internaldiameter, the tube having an internal step or constriction to support aperforated plate on which the resin is supported. The resin column isWashed with mineral acid to convert it to acid form. A 0.01 to 0.1 Msolution in 1 to 2 N hydrochloric, nitric or perchloric acid ofzirconium oxychloride or other soluble zirconium salt and associatedhafnium impurity (in amount equal to about two percent by weight of thezirconium) was seeded with a tracer quantity of radioactive zirconium(Zr 95 and hafnium (Hf 181) and introduced into the top 'of the column.A total amount of solution equivalent to 10 gm. of zirconia could betreated by the quantity of resin in the column at one time. After2,759,793 Patented .21., a sea .-?2 :the solution had pas'sed throughthe-eolumn, aqueous t-N sulphuric acid was massed lthrongh ahe ---columnand zthe teluate'was continuously monitored hyme'ans of afGeiger-*Miiller tube and appropriateramplifier. :Eittemakcnunting ot thecoturnnrwa'salso carried rout.

When volume :of :elua'te w'a's 'p'lotted again-st :natli'oactivity asindicated thy t-heleluate arounteriavo distinct and widely -=separateti'banii's were obtained, 'ith'e Izireonixnn tiretspon'sible forlthefirstzbandzpassirrg quitelrapidlyzfromahe column-and th'e f'hafniumre'snl ting in fithe second band passing much more slowly. The eluateicollected 'duning the "first ba'n'd :contained :from 9:8 :to- 9.9 per:ceneof the zirconium ori'gin'ally :presenttand roxid'e precipitatedzfrom -'the solution showed ion tspectrographic analysis zless than 0.01per cent of zhafnium.

Hafnium remaining Lin like colnrnn "after 'JGOl'lEGflGl'l of thevzire'o'nium iwas zreadily removed zby felttti'ng with :a eomplexingagent for vthe tha'fnmm, preferably dilute ahydroflnnnic tacit-l of rforexample 0=05 rper cent won'c'entration. DlIutefa'queous oxalicaoidintaylb'e ms'erlsas Jalternative. After Washing thercolumn withmineral :acizi, a further batchvoftzi'reoniummalt/could 'be tt'riea'ted.If conditions as 'to concentrations and i'a'mounts are .ikfipt the same,N sulphuric acid eluate in amountsequal ltottltat em-responding ito the:first band would be tc'ollected .and "vwoul'dibe tfoundaovcontaintsubstantially all the zirconium of the purity specified above.

an a-Iterna'tive to'zthe above;ineth'od,zzirconiumrand liiS attendant vha'fnium rirnpurity may :be 'ibrought into solution in 0.8 to 1.2 Naqueous sulphuric :acid .andzthe solutionqaassed:onstorareolnnmof"iDowexifiO resin, or :s'imilar :ron exchange :restn,'rpreviousl'yfrendere'd faeid 'l'iytrreatmenowizhznormal:sulphuriczaeiu. zFnrt'herrsulphuric z-aeitl ofitlre normality ius'ed :for the solution may then he :passed 'throughTthe column ':to :complete tthe #elntinn. Eluate :is collectedthroughout :the mm and lithe first "dractti'onsrof it will ieontain:zireonium :havin :a :lrafnium content less thamOtDS per cent.iwhereihydrofluori'cracidZis .usc'd Ito lelute l h'afniu'm, it :may :befound r'prefierable to employer :perspex cor zI-su'eitettuheztovlrold(the :cationieieachangezmat'erial.

sfirom mms with rotherieluting age'nts tit is :concluded that theseparation obtained is due to difference in complexing behaviour. Thuswith 3 N perchloric acid, a solution in which zirconium is believed tobe little complexed, the zirconium and hafnium show very little tendencyto move down the column. With 3 N hydrochloric acid considerable butinadequate separation was achieved and the hafnium was eluted first, andhigher concentrations of acid gave smaller separations. 3 N nitric acidshowed no separation, although the one band observed moved down thecolumn at the same rate as did the zirconium band when 3 N hydrochloricacid was used. The latter is in agreement with an observation by Connickand McVey (J. A. C. S. 71, 3182 (1949)) that zirconium is equallycomplexed in solutions of 2 N hydrochloric and nitric acids.

We claim:

1. A method of separating zirconium and hafnium which compriseseffecting adsorption of salts of the metals on a cation exchangematerial and eluting the cation exchange material and the adsorbate withsulphuric acid of concentration 0.8 N to 1.2 N, and segregating theinitial eluate containing zirconium.

2. A method of recovery of zirconium substantially free from hafniumfrom cation exchange material on which the substances are adsorbed, themethod comprising eluting the cation exchange material with 0.8 N to 1.5N sulphuric acid and segregating initial eluate containing zirconium.

3. A method of separating zirconium from hafnium which comprisesbringing a solution of salts of the metals resin to bring aboutadsorption of the metals on the resin, eluting the said resin with 0.8 Nto 1.5 N sulphuric acid to recover zirconium substantially free fromhafnium and then removing hafnium adsorbed on the resin by eluting witha complexing agent for the hafnium.

4. A method of recovery of zirconium substantially free from hafniumwherein a solution of salts of the metals in aqueous mineral acid isbrought into contact with sulphonated polystyrene ion exchange resin tobring about adsorption of the metals by the said resin and eluting theresin with 0.8 to 1.5 normal sulphuric and collecting separately theinitial part of the eluate containing the greater part of the zirconiumwithout appreciable quantity of hafnium.

5. A method of recovering zirconium substantially free from hafniumwherein a 0.01 M solution of zirconium oxychloride and attendant hafniumimpurity in substantially 2 N mineral acid is brought into contact withsulphonated polystyrene ion exchange resin in the acid condition tobring about adsorption of the metals on the said resin, eluting theresin with substantially normal aqueous sulphuric acid and collectingseparately the initial eluate containing the greater part of thezirconium without appreciable content of hafnium.

6. A method according to claim 5 wherein the treated solution ofzirconium oxychloride is substantially 2 N in hydrochloric acid.

7. A method according to claim 5 wherein the treated .solution ofzirconium oxychloride is substantially 2 N in nitric acid.

8. A method according to claim 5 wherein the treated solution ofzirconium oxychloride is substantially 2 N in perchloric acid.

9. A method of producing zirconium substantially free from hafnium whichcomprises passing a solution in 0.8 to 1.5 N sulphuric acid of zirconiumcontaining hafnium into contact with a mass of sulphonated polystyreneion exchange resin, collecting zirconium-containing solution leaving theresin mass, eluting the resin mass with 0.8 to 1.5 N sulphuric acid andcollecting initial eluate containing zirconium substantially free fromhafnium.

10. A method of producing zirconium substantially free from hafniumwhich comprises passing a 0.8 to 1.5 N sulphuric acidzirconium-containing solution through a column of sulphonatedpolystyrene ion exchange resin,

collecting substantially hafnium-free zirconium-containing solutionleaving the column, eluting the column of resin with 0.8 to 1.5 Nsulphuric acid collecting initial eluate containing zirconiumsubstantially free from hafnium.

11. A method of recovering zirconium substantially free from hafniumfrom an impure zirconium salt wherein the impure zirconium salt insolution in aqueous nitric acid is passed through a column ofsulphonated polystyrene ion exchange resin in acid condition to bringabout adsorption of the metals Zirconium and hafnium on the said resin,the column of resin is eluted with 0.8 M to 1.5 M aqueous sulphuric acidand the initial portion of eluate from the column of resin containingthe greater part of the zirconium with a substantially reduced hafniumcontent is collected separately.

12. A method according to claim 11 wherein hafnium retained by the resincolumn is subsequently eluted by means of a complexing agent for thehafnium.

13. A method according to claim 11 wherein hafnium retained by thecolumn of resin is subsequently eluted with an aqueous solution ofoxalic acid.

14. A method of recovering zirconium substantially free from hafnium,wherein impure zirconium salt in solution in aqueous nitric acid ispassed through a column of a cation exchange material to bring aboutadsorption of the metals zirconium and hafnium on the ion exchangematerial and the latter is eluted with 0.8 M to 1.5 M sulphuric acid toremove zirconium from the ion exchange material, the elution isdiscontinued when the greater part of the zirconium substantially freefrom hafnium has been eluted, the eluate is collected, and the hafniumretained on the ion exchange material is eluted by means of a solutionof a complexing agent for hafnium and the hafnium-containing eluate iscollected separately.

References Cited in the file of this patent Industrial and EngineeringChemistry, vol. 40, pages 1350-5 (1948).

Ayres: Purification of Zirconium by Ion Exchange Columns, MDDC, 1026,June 30, 1947; U. S. Atomic Energy Commission.

Street et al.: The Ion Exchange Separation of Zirconium and Hafnium,AECD 2435, October 11, 1943; U. S. Atomic Energy Commission, 2 pages.

1. A METHOD OF SEPARATING ZIRCONIUM AND HAFNIUM WHICH COMPRISES EFFECTING ADSORPTION OF SALTS OF THE METALS ON A CATION EXCHANGE MATERIAL AND ELUTING THE CATION EXCHANGE MATERIAL AND THE ADSORBATE WITH SULPHURIC ACID OF CONCENTRATION 0.8 N TO 1.2 N, AND SEGREGATING THE INITIAL ELUATE CONTAINING ZIRCONIUM. 